Question

Please answer these questions in as long of detail as possible.

Question 1

a) Write the expression used to calculate rate of digestion as it’s related to starch concentration and time:

b) Explain what a catalytic process is and how it is different from the non-catalytic version of the process. Give an example of an enzymatic process other than amylase and describe the substrate(s)/product(s):

c) Describe what the enzyme amylase does and what would happen in the absence of this enzyme:

Answer 1

Ans. #a. The rate of digestion of starch is indirectly measured as the rate of production of glucose (the product of starch digestion) during the reaction.

            Rate of starch hydrolysis = Rate of glucose production

            Or, Rate of starch hydrolysis = Increase in [Glucose] / Time of reaction

#b. A catalyst is non-reactive chemical species that increases the rate of reaction by lowering the activation energy of the reaction.

# A reaction/process being carried out in presence of a catalyst is called a catalytic process.

# The rate of catalyzed-reaction is greater than that of un-catalyzed reaction.

# Digestion of proteins in small intestine by proteases (trypsin, chymotrypsin, carboxypeptidases, etc.) is an enzymatic process. During the reaction, proteins (substrate) are finally hydrolyzed into free amino acids (product).

#c. Starch is a heterogenous homopolymer of glucose consisting of amylose (? 20-25%) and amylopectin (75-80%). Amylose is an unbranched polymer of ?-D-glucose linked together by ? (1?4) glycosidic bond. Amylopectin is a branched homopolymer of ?-D-glucose linked together by ? (1?4) glycosidic bond.

Amylase randomly hydrolyzes starch into small fragments called dextrin (a group of heterogenous short polymers of D-glucose linked together by ? (1?4) or ? (1?6) glycosidic bond). Dextrin is further hydrolyzed into disaccharide maltose by the same enzyme. Maltose is finally hydrolyzed into its monomers glucose by maltase. The glucose thus produced gives positive result with Benedict’s reagent (red color) or can be measured spectrophotometrically to determine the rate of hydrolysis.

# In absence of amylase, starch won’t be hydrolyzed into glucose. So, the reaction mixture in absence of amylase does not give a positive result of Benedict’s test, or [Glucose] remains unaffected over time.